Electromagnetic interference is a disturbance that negatively impacts electronic components and circuitry due to an electromagnetic radiation, i.e. a magnetic field, from an external source. In addition to natural electromagnetic radiation, a significant source of external magnetic fields are electronics found in many objects and devices including automobiles, cellular phones, and computers.
Electromagnetic shielding is a common practice in which a barrier of a conductive or magnetic material is used in an enclosure or housing to isolate electronic components from unwanted electromagnetic interference. Electromagnetic shielding can further be applied to prevent electronic components enclosed within the shield from emitting electromagnetic radiation and contributing to an external magnetic field seen by another electronic component. Typical shielding materials include sheet metal, metal coatings applied to a surface, or fine metal screens.
A modern automobile has many discrete electronic components and systems located in various positions throughout the automobile. Exemplary systems include electronic control units (ECUs) for engine control, transmission control, chassis control, passenger comfort systems, and infotainment systems. These ECUs are often enclosed within housings formed from plastics or resins.
As more ECUs are used throughout the automobile, there is an increased need for effective magnetic shielding to prevent unwanted magnetic fields generated by these electronic systems from negatively impacting system performance. However, traditional shielding materials are comparatively heavy relative to the housing material and add significant weight when used throughout an automobile.
Electromagnetic radiation is also generated at specific points on an ECU board. For example, a transformer or other lumped component on the ECU board may generate a significant magnetic field while the remainder of the ECU board generates an insignificant amount of electromagnetic radiation. However, traditional magnetic shields are unable to target specific sources of electromagnetic radiation within the housing and must be applied throughout the entire housing to be effective.
It would therefore be useful to shield unwanted magnetic fields by altering the spatial distribution of a magnetic field emitted by a source with a lightweight magnetic field shield incorporated into a housing for an electronic component.